OBJECTIVES: 5S RNA: 1. a) To determine conclusively whether G44 and 5S RNA reacts or does not react with kethoxal when ribosomes are engaged in an initiation complex. b) To determine if there are structure changes in 5S RNA with ribosome in an initiation complex, other than a possible G44 reaction. 2. a) To determine whether selective reaction of G44 can be achieved with reaction of 5S RNA in solution. If so, reconstitution with modified RNA & function studies will be done. b) To determine whether variations of Mg ions, K ion or temperature and reactions with kethoxal will provide information on tertiary structure of 5S RNA in solution. Streptomycin Binding: 3. To determine whether SM or DSM binds covalently to natural RNA's to the extent that it binds to synthetic RNA's. Diazide of Ethidium Bromide: 4. To determine whether a protein synthesis initiation complex is stable to a reaction with the diazide of ethidium bromide. It it is, then cross-linking with the photo-affinity label will be used to cross-link fMet tRNA to ribosomal components and determine interaction molecules. Phosphorylation of Proteins: 5. To determine changes in the phosphorylation of ribosomal proteins with infection with reovirus.